1. Field of the Invention
The present invention relates to a substrate processing apparatus for processing a substrate while the substrate is held by a substrate holding and rotating mechanism, and also to a substrate transferring method in such a substrate processing apparatus. Examples of the substrate to be processed or transferred include a semiconductor wafer, a liquid crystal display substrate, a plasma display substrate, an FED (Field Emission Display) substrate, an optical-disk substrate, a magnetic-disk substrate, a magneto-optical-disk substrate, a photomask substrate and the like.
2. Description of Related Art
A substrate processing apparatus for processing a substrate such as a semiconductor wafer or the like, has a spin chuck for holding and rotating a substrate, and a treatment liquid nozzle for supplying a treatment liquid to the substrate held by the spin chuck. The spin chuck includes a disk-like base member, and a plurality of holding pins which stand from the peripheral edge of the base member and which are arranged to come in contact with the peripheral end face of a substrate, thereby to hold the substrate.
According to the above-mentioned arrangement, however, the portions of the substrate peripheral end face coming in contact with the holding pins remain unprocessed. Such unprocessed portions are a problem, particularly in a bevel etching or a bevel washing treatment for removing an unnecessary copper film and copper ions at the substrate peripheral edge and on the peripheral end face after the copper film is formed on the substrate surface. Such unprocessed portions may provoke a metal contamination to a substrate holding hand when the substrate is thereafter transferred by a substrate transfer robot. Then such metal contamination may be further transferred to other substrate, causing a diffusion of metal contamination to various components of the substrate processing apparatus.
To overcome the above-mentioned problem, the prior art disclosed in the U.S. Patent Application Publication No. US 2005/276921 A1 proposes an arrangement in which a substrate is supported from the underside thereof by a substrate supporting member implanted in a rotary base member, while the substrate is pushed to the substrate supporting member by supplying gas onto the top of the substrate, so that the substrate is rotated while being held by the friction between the substrate supporting member and the substrate.
According to the above-mentioned arrangement, however, it is essential that the substrate is supported in an accurate alignment, on the substrate supporting member. If the axis of rotation of the rotary base member is not aligned with the gravity center of the substrate, the substrate tends to move horizontally by the centrifugal force with the rotation. This may cause unstablity for holding the substrate.
It is therefore proposed that in the course of the transfer of a substrate by a substrate transfer robot, the substrate is aligned with the substrate holding hand or an unprocessed substrate is once carried in an alignment stage for alignment thereof. It is also proposed to use a substrate transfer robot of high precision to secure the necessary positional precision.
However, any of these measures is highly expensive and is therefore not preferable. Further, it is practically impossible to achieve the necessary positional precision due to tolerance of the parts and variations of assembling thereof.